Flexible doors of the general type wherein a drive mechanism for raising and lowering the door includes an electrically powered motor which applies torque to a roller causing the door to wind up on or to unwind from the roller in positioning the door in either the open or closed position, or any position therebetween. The flexible curtain is typically comprised of a lightweight, strong fabric material and the electric motor is typically connected to the roller mechanism via a reduction gear to reduce the number of revolutions of the electric motor per unit distance of travel of the flexible door. Movable structures of this type can be used either to cover an opening, such as a doorway in a building structure, or they be used as a movable partition, or curtain, in the structure.
When used as a partition, or curtain, this roll-up structure may span large distances in the building structure. These types of flexible curtains isolate the inside of the building structure from the elements, such as wind, rain, snow and sunlight, while permitting the building structure to be opened up so as to provide access to the outside when the environment is more hospitable.
As the applications for these types of flexible curtains have increased, additional demands have been placed on their structure and operation. For example, these types of flexible curtains are being used to span increasingly longer distances within the building structure. This, of course, places increasing demands upon the curtain support and drive, or displacement, system. Higher power ratings are required for the curtain drive mechanism, which typically includes an electrically powered motor, for increasing heights and horizontal distances spanned by the curtain. In addition, the curtain support system, which typically is in the form of a horizontal, elongated rod, must be stronger to accommodate the increased weight of curtains spanning larger openings and must itself be lightweight to compensate for the increased weight of the curtain. This further increases the power requirements to operate the flexible curtain. Where a roll-up rod is attached to a lower end of the flexible curtain, a complicated displacement and support mechanism is typically required to accommodate vertical movement of the rod.
The present invention addresses the aforementioned limitations of the prior art by providing a multi-section roll-up curtain assembly including plural, vertically spaced, horizontal roll-up rods each extending across an opening and attached to a respective section of the curtain. Each of the rods is coupled to and rotated by a respective electric motor, with the electric motors connected and vertically displaced with the curtain either upward or downward in retracting or extending the curtain sections in unison.